Heat exchanger



MalCh 20, 1952 L. c. PELLEGRINI 3,026,092

HEAT EXCHANGER Filed Aug. 18. 1958 4 Sheets-Shed'l 1 5f.' 7/ t ATT'KMarch 20, 1962 c. PELLEGRINI HEAT EXCHANGER 4 Sheets-Sheet 2 Filed Aug.18. 1958 March 20, 1962 L. c. PELLI-:GRNy 3,026,092

HEAT EXCHANGER Filed Aug. 18, 1958 4 Sheets-Sheet 3 Mardi 20, 1962 C.PELLEGRINI HEAT EXCHANGER 4 Sheets-Sheet 4 Filed Aug. 18. 1958 F/qlzUnited States Patent 3,926,692 HEAT EXCHANGER Louis C. Pellegrini, St.Louis, Mo., assigner to Marlo Coil Company, St. Louis, Mo., acorporation oi Missouri Fiied Aug. 18, 1958, Ser. No. 755,607 Claims.(Cl. 257-50) 'Ihis invention Arelates to improvements in heat exchanger.More particularly, this invention relates to improvements insteam-heated, air-heating, heat exchangers.

lt is therefore an object of the present invention to provide animproved steam-heated, air-heating, heat exchanger.

lt is frequently desirable in the manufacture of steamheated,air-heating heat exchangers to make those heat exchangers so they havethe tubes thereof alined in rows, and so the rows of tubes are laterallyspaced apart. It would be desirable to mount all of the tubes oi thevarious rows of tubes in just one set of iins because such anarrangement would obviate any and all of the misalignment of fins thatalways occurs when individually-finned rows of tubes are set inface-to-ace relation. By obviating that misalignment, it is possible todecrease the accumulations of lint and dirt in the heat exchanger andthereby decrease the pressure drop across that heat exchanger. While itlong has been recognized that it would be desirable to mount all of thetubes of the various rows of tubes in just one set of iins, it hasheretofore been regarded as impractical to mount more than two rows oftubes in just one set of tins of a steam-heated, air-heating heatexchanger, particularly where that heat exchanger operatesintermittently.

lt has heretofore been regarded as impractical to mount more than tworows of tubes in just one set of fins of a steam-heated, air-heatingheat exchanger because of the warping of the heat exchanger as the hotsteam rushes into the tubes and the cold air engages the fins and theexteriors of the tubes. Under some extreme circumstances, thetemperature of the steam can be as high as three hundred and eightyseven degrees Fahrenheit and the temperature of the air can be as low asthirty degrees below zero. The contractions of certain parts of the heatexchanger caused by the impingrnent of the very cold air on th-ose partsof that heat exchanger coact with the expansions of the tubes of thatheat exchanger caused by the inrush of the very hot steam into thosetubes to cause a working and warping of the heat exchanger that isdestructive. The present invention obviates this destructive working andwarping of the heat exchanger and thereby makes it possible to makesteam-heated, air-heating, heat exchangers which have at least four rowsof tubes mounted in just one set of tins. lt is therefore an object ofthe present invention to provide a steam-heated, air-heating, heatexchanger which has at least four rows of tubes mounted in just one setof tins.

The present invention reduces the contractions and expansions of theheat exchanger by mounting imperforate tubes in the iins and byintroducing the steam into perforated tubes telescoped into thoseimperforate tubes. The present invention further reduces thecontractions and expansions of the heat exchanger by introducing part ofthe steam at one end of the heat exchanger and by introducing the restof the steam at the other end of that heat exchanger. The telescoping ofthe perforated tubes within the irnperforate tubes minimizes thetemperature gradient alc-ng the face of the heat exchanger, and theintroduction of the steam from both ends of the heat exchanger alsominimizes that temperature gradient. Fihe overall result is that workingor warping of the heat exchanger is minimized. It is therefore an objectof the present in- 3,026,092 Patented Mar. 20, 1952 ice Vention toprovide a steam-heated, air-heating, heat exchanger wherein the steam isintroduced into perforated tubes telescoped within imperforate tubes andwherein the steam is introduced at both ends of said heat exchanger.

The introduction of the steam at both ends of the heat exchanger isadditionally advantageous where the steam is throttled. Ordinarily thethrottling of steam in a steamheated, air-heating, heat exchanger leadsto the existence of cold spots at the far end of the heat exchanger, andto the issuance of unheated air from that end of the heat exchanger.With the heat exchanger of the present invention, all parts of the heatexchanger will be hot even when the steam is throttled.

Other and further objects and advantages of the present invention shouldbecome apparent from an examination of the drawing and accompanyingdescription.

In the drawing and accompanying description several preferredembodiments of the present invention have been shown and described butit is to be understood that the drawing and accompanying description arefor the purpose of illustration only and do not limit the invention andythat the invention will be defined by the appended claims.

In the drawing:

FiG. 1 is a partially-broken, plan view of one embodiment ofsteam-heated, air-heating, heat exchanger that is made in accordancewith the principles and teachings of the present invention,

FIG. 2 is a partially-broken, plan view of another embodiment ofsteam-heated, air-heating, heat exchanger that is made in accordancewith the principles and teachings of the present invention,

FIG. 3 is a partially-sectioned, plan view of part of another embodimentof steam-heated, air-heating, heat exchanger that is made in accordancewith the principles and teachings of the present invention,

FlG. 4 is another partially-sectioned, plan View through the heatexchanger of FIG. 3, and it is taken through the tube immediately abovethe tube shown in FIG. 3,

FlG. 5 is a sectional plan view of another embodiment of steam-heated,air-heating, heat exchanger that is made in accordance with theprinciples and teachings of the present invention,

FIG. 6 is a plan view of another embodiment of steamheated, air-heating,heat exchanger that is made in accordance with the principles andteachings of the present invention,

FIG. 7 is a front elevational view of the heat exchanger of FIG. 6, Y

FEG. 8 is a sectional plan view, on an enlarged scale, of a portion ofthe heat exchanger of FIGS. 6 and 7, and it is taken along the planeindicated by the line 8-8 in FIG. 7,

FIG. 9 is a partially-broken, elevational view of the lefthand end ofthe heat exchanger of FIGS. 6 and 7,

FiG. l0 is a partially-broken elevational view of the right-hand end ofthe heat exchanger of FIGS. 6 and 7, and

FIG. 1l is a diagrammatic, plan view of still another embodiment ofsteam-heated, air-heating, heat exchange that is made in accordance withthe principles and teachings of the present invention.

Referring to the drawing in detail, the numeral 2% generally denotes theframe of a steam-heated, air-heating, heat exchanger that is made inaccordance with the principles and teachings of the present invention.While that frame could be made in many different Ways, it is shown asbeing made of a series of channel-like structural members. The frame 20extends laterally outwardly beyond the edges of, and thereby protects,heat-exchanging fins v 22. Each of those fins has been punched toprovideiour spaanse laterally-spaced, vertically-directed rows ofopenings; and those tins will preferably be made from a metal having ahigh thermal conductivity such as copper, aluminum or the like.Imperforate-wall tubes 24, 26, 28 and 3&3 of metal having a relativelyhigh thermal conductivity are disposed within the uppermost openings inthe ns 22; and a number of identically similar tubes are within thoseopenings in tins 22 which are below, butin vertical alinement with,those uppermost openings. As a result, four laterally-spaced,vertically-directed rows of tubes are mounted in the fins 22. Thosevarous tubes will be suitably iixed within those openings in one of theways known to those skilled in the art.

A condensate header 32 is provided at the left-hand end of the heatexchanger of FIG. 1; and the tubes 24, 26, 28 and 30 and theircounterparts incline downwardly from right to left in FIG. l so thelowermost ends thereof are adjacent the condensate header 32. The tubes24, 26, 28 and 30 and their counterparts extend into appropriateopenings in the wall of the condensate header 32 so the condensate whichforms in those tubes can readily drain into that header. A condensatereturn line 34 is connected to the condensate header 32 adjacent thebottom thereof, and that return line inclines downwardly from itsconnection with header 32 to provide ready drainage of the condensate.

A tube 36 which has a ninety degree bend intermediate the ends thereofand which has a number of openings or perforations 38 in one arm thereofextends through the right-hand end of the tube 24. The left-hand end ofthe perforated arm of tube 36 is closed, and the righthand end of thetube 24 ts tightly around the righthand end of the perforated arm oftube 36 and is sealed to that arm of that tube. The openings orperforations 38 are distributed both axially and circumferentially alongthe length of the said arm of the tube 36. A tube 40 which has a ninetydegree bend intermediate the ends thereof and which has one arm thereofprovided with openings or perforations 38 extends through the righthandend of tube 30. The left-hand end of the perforated arm of tube 40 isclosed, and the right-hand end of the tube 30 closely fits around thetube 40 and is sealed to it. The other arms of the tubes 36 and 40extend to and communicate with a steam header 42. That header suppliessteam to the tubes 36 and 4i), and that steam will issue from theopenings or perforations 38 and enter the imperforate tubes 24 and 30. Aseries of tubes, identically similar to the tubes 36 and 40, are mountedbelow but in vertical registry with the tubes 36 and 40, any they extendthrough the right-hand ends of the tubes which are below but in verticalregistry with the tubes 24 and 30.

A tube 44 which has a ninety degree bend intermediate the ends thereofpasses through an opening in the lefthand side of the condensate header32, and the junction between that opening and that tube is hermeticallysealed. One arm of the tube 44 extends through the header 32 and extendsinto the tube 26. That arm has a number of perforations 38 disposedalong its length but its righthand end is closed. A tube 46 which has aninety degree bend'intermediate the ends thereof passes through anotheropening in the left-hand side of condensate header 32, and the junctionbetween that opening and that tube is hermetically sealed. One arm ofthetube 46 extends through the header 32 and extends into the tube 2S. Thatarm has a number of openings 38 disposed along its length, .but itsright-hand end is closed. The other arms of the tubes 44 and 46 extendto and communicate with a steam header 48. A number of tubes,identically similar to the tubes 44 and 46, are disposed below but invertical registry with the tubes 44 and 46; and those tubes extendbetween the header 48 and thosetubes which are below but in verticalregistry with the tubes 26 and 28. A main steam supply pipe 50 extendsto the header 48 and supplies steam thereto; and a smaller steam supply4 pipe 52 extends between that header and the header 42 to supply steamto that latter header.

In the operation of the heat exchanger shown in FIG. 1, steam isintroduced into the header 4S by the supply pipe 50, and some of thatsteam is introduced into the header 42 by the supply pipe 52. Part ofthe steam introduced into the header 48 will pass through the tubes 44and 46, and their counterparts, and pass through the openings 38 toenter the tubes 26 and 28 and their counterparts. The perforated tubes44 and 46, and their counterparts, tend to distribute the steam alongthe lengths of the imperforate tubes 26 and 28 and their counterparts;and that steam will engage the inner walls of the tubes 26 and 28 andtheir counterparts and thereby transfer its heat to those walls. As thesteam transfers its heat it will condense, and the resulting condensatewill ilow toward the lowermost ends of tubes 26 and 28 and entercondensate header 32. The steam introduced into the header 42 will passinto the tubes 36 and 40, and their counterparts, and will pass throughthe openings 38 into the tubes 24 and 30 and their counterparts. Thatsteam will engage the inner walls of the tubes 24 and 30, and theircounterparts, and will transfer Vits heat to those Walls. As the steamtransfers its heat to those walls it will condense, and the resultingcondensate flow toward the lowermost ends of tubes 24 and 30 and entercondensate header 32. The condensate formed in tubes 24 and 30, andtheir counterparts, will flow in the same direction in which the steamwithin tubes 36 and 4G, and their counterparts, ows; whereas thecondensate formed in tubes 26 and 28, and their counterparts, must ow inthe opposite direction to which the steam within tubes 44 and 46, andtheir counterparts, ows.

It will be noted that one half of the steam supplied to the heatexchanger is introduced at the left-hand end of that heat exchanger, andthat the rest of that steam is introduced at the right-hand end of thatheat exchanger. This means that the temperature gradient along the faceof the heat exchanger will be very small, and that the temperatures ofmost parts of the heat exchanger will be held within a completelyworkable and practical range. Further, this will still be the case whenthe steam is throttled. In prior, steam-heated, air-heating, heatexchangers, the steam has been introduced at just one end of the heatexchanger; and throttling of the steam permitted the opposite end of theheat exchanger to become cool. Consequently, the air issuing from thatend of the heat exchanger was not heated adequately, and could produce acool draft rather than a Warm flow of air. With the heat exchangerprovided by the present invention, all of the air issuing from that heatexchanger will be warmed, even when the steam has been throttled.

It will be noted that there is no misalignment of the heat-exchangingtins for the adjacent rows of tubes because all of the rows of tubes aremounted in just one set of tins. Hence, there is not the usualinterruption to the smooth ow of air through the heat exchanger, thereis not the usual frictional losses, and there is not the usual pressuredrop.

Referring to FIG. 27 the numeral 60 denotes the frame of a heatexchanger, and that frame protects and supports tins 62. Each of thoseVtins has been punched to provide four rows of aligned openings, andthose openings accommodate four laterally-spaced, vertically-alignedrows of imperforate tubes. The uppermost tubes of those rows of tubesare denoted by the numerals 64, 66, 68 and 70. The tubes 64 and 66, andtheirrcounterparts, incline downwardly from right to left in FG. 2, andtheir lowermost ends are connected to and communicate with thecondensateV header 72. A condensate Yreturn 74 inclines downwardly andaway from the lower part of the header 72. The tubes 68 and 70, andtheir counterparts, incline downwardly from right to left in FIG.V 2 andtheir lowermost ends are connected to and communicate with thecondensate header 76. A condensate return 78 inclines downwardly andaway from the lower end of the header 76. if desired, one largecondensate header could be used instead of the two headers 72 and 76;and, if desired, some of the rows of tubes could be set to drain towarda condensate header at the righthand end of the heat exchanger while therest of the rows of tubes drained toward a condensate header at theleft-hand end of the heat exchanger. Because of the possibility of usingdifferent numbers and arrangements of condensate headers, it will beunderstood that whenever the phrase condensate header is used herein orin the claims hereof it will be understood, unless expressly orimpliedly indicated otherwise, to mean one or more condensate headers.

A tube 89 has a ninety degree bend intermediate the ends thereof, andone arm of that tube has perforations 3S therein. That arm of that tubeextends through the right-hand end of the tube 64 and is sealed to thatlatter tube. identically similar tubes are disposed below but invertical registry with the tube Si?, and the arms of those tubes extendinto the tubes which are the counterparts of tube 64. The left-hand endsof tube 30 and its counterparts are closed. The numeral 82 denotesanother tube with a ninety degree bend intermediate its ends, and onearm of that tube has perforations 38. That arm of that tube extendsthrough the right-hand end of the tube 68 and is sealed to that lattertube. Other tubes, identically similar to the tube 82, are below but invertical registry with that tube and extend into the tubes which are thecounterparts of the tube 68. rIhe other arms of the tubes St? and 82 andtheir counterparts extend to and communicate with the steam header 84.

The numeral 86 denotes a generally J-shaped tube which has the long armthereof provided with perforations 38. That arm, which has itsright-hand end closed, extends through an opening in the left side ofthe header 72 and extends into the tube 66. A number of tubesidentically similar to the tube 86 are disposed below but in verticalregistry with that tube, and they extend through other openings in theleft side of header 72 and lodge within the tubes which are thecounterparts of tube 66. The numeral 88 denotes another J-shaped tubewhich has its long arm provided with openings 38. That arm has itsright-hand end closed, and it telescopes through an opening in the leftside of header 76 and lodges in the tube 70. The counterparts of tube SSalso extend through openings in the left side of header 76 and lodge inthe counterparts of tube 70. The short arms of the tubes S6 and 33 areconnected to and communicate with the steam header 9b. That steam headeris connected to the steam header S4 by a steam supply pipe 94, and itreceives steam from steam supply pipe 92.

The construction and operation of the heat exchanger shown in FiG. 2 issimilar to that of the heat exchanger shown in FIG. l; the principaldierences between the two heat exchangers being in the interleaving ofthe oppositeiy fired or fed tubes of the heat exchanger of FlG. 2, andthe use of two, rather than just one, condensate header. In each heatexchanger, two rows of tubes are tired or fed from the right-hand end ofthe heat exchanger and two rows of tubes are fed from the left-hand endof the heat exchanger.

Referring to FGS. 3 and 4, the numeral $.60 denotes the heat-exchanginghns of a single row heat exchanger. Those tins support a number of tubes1&2 and ldd and their counterparts; and those tubes incline downwardlyfrom left to right in FiGS. 3 and 4. The tubes 162 and E04, and theircounterparts, are interleaved vertically; and the tube ftd-t and itscounterparts have closed left-hand ends 12S. while the tube 162 and itscounterparts have openings in the left-hand ends 1&6 thereof.

A Tube ltSand its counterparts have ninety degree bends intermediate theends thereof; and while the right-hand ends of the long arms of thosetubes are closed, a number of perforations or openings 38 aredistributed axially and circumferentially along those arms. The shortarms of the tube 108 and its counterparts extend to and cornmunicatewith the steam header and the long arms of those tubes telescope throughand are sealed to the openings in the left-` and ends of the tube 102and its counterparts. The right-hand ends of the tube 102 and itscounterparts extend to and communicate with the condensate header 122.That condensate header is provided with a condensate return 124 whichinclines downwardly and away from the bottom of the header 122.

Tube 26 und its counterparts have ninety degree bends intermediate theends thereof, and the long arms of those tubes extend through openingsin the right side of the condensate header 122 and telescope into thetube 194 and its counterparts. The right-hand ends of tube iti-t and itscounterparts extend to and communicate with the condensate header 122.The other arms of the tube 126 and its counterparts extend to andcommunicate with the steam header 130. That steam header is connectedwith the steam header 1Z0 by a steam pipe 134; and the steam header 130is supplied with steam by a steam supply pipe 132.

In the operation of the heat exchanger shown in FiGS. 3 and 4, part ofthe steam from supply pipe 132 passes into the header 136 and then intothe tube 126 and its counterparts. That part of the steam passesoutwardly through the openings 38 and enters the imperforate tube 1b?.-and its counterparts. The rest of the steam passes through supply pipe134 to header 126 and then into die tube 108 and its counterparts.Thereafter, the said rest ot the steam passes through the openings 38and enters the imperforate tube 1912 and its counterparts. The steamwhich enters the imperforate tubes 102 and t4 and their counterpartswill engage the inner surfaces of those tubes and transfer their heat tothose tubes. In doing so, that steam will condense; and the resultingcondensate will flow toward the lowermost ends of tubes 102 and 104 andtheir counterparts and enter the condensate header 122. Thereafter, thatcondensate will drain through the condensate return 124. The operationof the heat exchanger of FIGS. 3 and 4 is similar to the operation ofthe heat exchangers of FIGS. 1 and 2; the principal differences beingthat the heat exchanger of FGS. 3 and 4 is a single row heat exchangerand that the tubes 162 and 104 and their counterparts `are verticallyinterleaved.

Referring to FIG. 5, the numeral 140 denotes a number of heat-exchangingns which are punched to provide two laterally-spaced rows of alinedopenings. Those openings accommodate imperorate tubes 142 and 144 andtheir counterparts; and those tubes incline downwardly from left toright in FIG. 5. The right-hand ends of those tubes extend to andcommunicate with a condensate header 150. A tube 1:74 and itscounterparts have ninety degree bends intermediate the ends thereof, andthe long arms of those tubes extend through and are sealed to the ends146 of the tube ido; and its counterparts. The righthand ends of thelong arms of tube 3.54 and its counterparts are closed, but those armshave openings 33 along the lengths thereof. The other arms of tube 154and its counterparts extend to and communicate with the steam header156.

The tube 144 and its counterparts have ciosure 14S at the left-hand endsthereof. Tube rS and its counterparts have ninety degree bendsintermediate the ends thereof, and the long arms of those tubes extendthrough openings in the right side of the condensate header It-3 andlodge within the tube 144 and its counterparts. The left-hand ends oftube 58 and its counterparts are closed, but the long arms of thosetubes have openings 3S along the lengths thereof. The junctions betweenthe long arms of tube 158 and its counterparts and the openings in theright side of header 15% are hermetically sealed. The short arms of tubeSS and its counterparts extend to and communicate with the steam header16). A steam supply pipe 164 extends between the header 168 and theheader 156, and a main steam supply pipe 162 is connected to the header160.

The heat exchanger shown in FIG. is similar to the heat exchanger shownin FIGS. 3 and 4; the principal difference being that the heat exchangerof FIG. 5 has two rows and has all of the tubes in one row fed at theirleft-hand ends and has all of the tubes in the other row fed at theirright-hand ends. The steam that passes through tubes 154 and 158 andenters tubes 142 and 144 will condense; and the resulting condensatewill flow downwardly to the condensate 4header 150 and drain out throughthe condensate return 152.

Referring to FIGS. 6-10, the numeral 17) denotes a frame for a heatexchanger, and the numeral 172 denotes a steam supply pipe. That pipe isconnected to the steam header 174, and a steam supply pipe 176 extendsfrom the header 174 to the steam header 178. As indicated particularlyin FiG. 7, the steam pipes 172 and 176 are located approximately midwaybetween the top and bottom of the heat exhanger. A condensate return 180is provided, and that return communicates with the bottom of condensateheader 182.

v A number of heat-exchanging ns 171 are mounted in the frame 170; andthose ns are punched to provide two laterally-spaced rows of openings.Imperforate tubes 184 and 188 and their counterparts are mounted inthose openings to define two laterally-spaced rows of tubes. Those tubesincline downwardly from right to left in FIGS. 6 and 7, and thelowermost ends of those tubes are connected to and communicate with thecondensate header 182. The right-hand ends of the tube 184 and itscounterparts are closed, and the right-hand ends of the tube 188 and itscounterparts are partially closed. Tube 198 and its counterparts haveninety degree bends intermediate the ends thereof, and the long arms ofthose tubes have their ends closed and have openings 38 along thelengths thereof. A tube 1S6-and its counterparts have bends ofapproximately two hundred and ninety degrees therein; and the long armsof those tubes have the ends thereof closed and they extend throughopenings in the left side of header 182 and lodge within tube 184 andits counterparts. The junctions between the tube 186 and itscounterparts and the openings in the left side of header 182 arehermetically sealed. The other Varms of tube 190 and its counterpartsextend to and communicate with steam header 178, and the other arms oftube 136 and its counterparts extend to and communicate with steamheader 174. The heat exchanger of FIGS. 6-10 is similar to the heatexchanger shown in FIG. 5, but the steam headers and the interconnectingsteam supply pipe 176 have been protected by the frame 176.

Referring to FIG. 1l, the numeral 2% denotes a steam supply pipe whichis connected to a steam header 282. A steam supply pipe 284 extends fromthe header 202 to the header 298, and that pipe has a shut o valve 286intermediate the ends thereof. The heat-exchanging fins 210 of the heatexchanger of FIG. il are punched to provide two laterally-spaced rows ofopenings, and tubes 212 and 216 and their counterparts are mounted inthose openings. Tube 212 and its counterparts extend between the steamheader 202 and the condensate header 214; and tube 216 and itscounterparts extend from the steam header 208 to the condensate header218. The two headers 214 and 218 are connected together by a condensateline 220, and a condensate return 222 extends downwardly and away fromthe lower end of the header 218.

In operation, the valve 206 can be opened to supply steam to the heatexchanger at both ends; and where that is done, part of the steam willpass from steam header 282 through tube 212 and its counterparts to thecondensate header 214, and the rest of the steam will pass When desired,the valve 286 can be set to reduce the amount of steam introduced intothe right-hand end of the heat exchanger.

in each of the heat exchangers shown by the drawing, heat-transferringns have been provided on the imperforate heat exchange tubes. However,the present invention is not restricted to use with heat exchangersutilizing finned tubes; that invention being usable with steamheated,heat exchangers that utilize bare tubes.

Whereas the drawing and accompanying description have shown anddescribed several preferred embodiments of the present invention, itshould be apparent to those skilled in the art that various changes maybe made in the form of the invention without affecting the scopethereof.

What I claim is:

l. A steam-heated, air-heating, heat exchanger that comprises a frame, aplurality of heat-exchanging fins disposed within said frame, each ofsaid heat-exchanging tins having a plurality of openings therein, saidopenings being grouped and alined to define at least fourlaterallyspaced rows of openings, a plurality of imperforate-wall tubesmounted in said openings in said heat-exchanging hns to `form at leastfour laterally-spaced rows of imperforate-wall tubes, saidimperforate-wall tubes being inclined to the horizontal and each of saidimperforatewall tubes having its lower end adjacent one end of saidframe, a condensate header that is adjacent said one end of said frameand that is connected to and communicates with the lower ends of saidimperforate-wall tubes, a steam header adjacent said one end of saidframe, a second steam header adjacent the opposite end of said frame, asteam pipe communicating With and extending between said steam headers,a plurality of perforatewall tubes that communicate with and extend fromthe first said steam header and that telescope into and through thelower ends of some of said imperforate-wall tubes, a second plurality ofperforate-wall tubes that communicate with and extend from saidsecond-steam header and that telescope into and through the upper endsof the rest of said imperforate-wall tubes, each of said perforate-walltubes having a bend therein intermediate its steam header and itsimperforate-wall tube, a portion of said perforate-Wall tubes beingsealed to and extending through said condensate header to telescope intotheir imperforate-wall tubes, said steam headers and said perforate-walltubes directing steam into the opposite ends of said heat exchanger, theperforations in each said perforate tube being spaced throughout itslength within the imperforate tube to provide uniform heating of saidheat exchanger even when said steam is throttled, said bends in saidperforate-Wall tubes accommodating expansion and contraction of said`perforate-wall tubes and of said imperforate-wall tubes, the upper endsof said some imperforate-wall tubes being closed, the upper ends of saidrest of said imperforate-wall tubes being sealed to said secondplurality of perforate-wall tubes, said frame extending laterallyoutwardly beyond the sides and end-s of said headers, the condensate insaid some imperforate-wall tubes flowing in a direction opposite to thedirection of flow Vof the steam in the rst said plurality ofperforate-Wall tubes, the condensate in said rest of saidimperforate-wall tubes iiowing in the same direction as the tlow of thesteam in said second plurality of perforate-wall tubes.

2. A steam-heated, air-heating, heat exchanger that comprises a frame, aplurality of heat-exchanging tins disposed within said frame, each ofsaid heat-exchanging iins having a plurality or' openings therein, saidopenings being grouped and alined to dene laterally-spaced rows ofopenings, a plurality of imperforate-wall tubes mounted in said openingsin said heat-exchanging fins to form laterally-spaced rows ofimperforate-Wall tubes, said imperforate-Wall. tubes being inclined tothe horizontal and each of said imperforate-wall tubes having its lowerend adjacent one end of said frame, a condensate header that is adjacentsaid one end of said frame and that is connected to and communicateswith the lower ends of said imperorate-wall tubes, a steam headeradjacent said one end of said frame, a second steam header adjacent theopposite end of said frame, a steam pipe communicating with andextending between said steam headers, a plurality of perforate-Walltubes that communicate with and extend from the iirst said steam headerand that telescope into and through the lower ends of some of saidimpertorate-wall tubes, a second plurality of perforate-wall tubes thatcommunicate with and extend from said second steam header and thattelescope into and through the upper ends of the rest of saidimperforate-wall tubes, each of said perorate-wall tubes having a bendtherein intermediate its steam header and its imperforate-wall tube, aportion of said perforate-wall tubes being sealed to and extendingthrough said condensate header to telescope into their imperforate-walltubes, said steam headers and said perforate-wall tubes directing steaminto the opposite ends of said heat exchanger, the perforations in eachsaid perorate tube being spaced throughout its length within theimperforate tube to provide uniform heating of said heat exchanger evenwhen said steam is throttled, Said bends in said perorate-wall tubesaccommodating expansion and contraction of said perforate-wall tubes andof said imperforate-wall tubes, the upper ends of said someimperforate-wall tubes being closed, the upper ends of said rest of saidimperforate-wall tubes being sealed to said second plurality ofperforate-wall tubes, the condensate in said some impertorate-wall tubesowing in a direction opposite to the direction of iiow of the steam inthe rst said plurality of perforate-wall tubes, the condensate in saidrest of said imperforate-wall tubes flowing in the same direction as theow of the steam in said second plurality of perforate-wall tubes.

3. A steam-heated, air-heating, heat exchanger that comprises a frame, aplurality of heat-exchanging tins disposed within said frame, each ofsaid heat-exchanging tins having a plurality of openings therein, saidopenings being grouped and alined to define at least fourlaterally-spaced rows of openings, a plurality of imperforate-wall tubesmounted in said openings in said heatexchanging tins to form at leastfour laterally-spaced rows of imperforate-wall tubes, saidimperforate-wall tubes being inclined to the horizontal to drain to thesame end ot the heat exchanger, a condensate header that is adjacentsaid frame and that is connected to and communicates with the lower endsof said imperforate-wall tubes, a steam header adjacent one end of saidframe, a second steam header adjacent the opposite end of said trame, asteam pipe communicating with and extending between said steam headers,a plurality of perforate-wall tubes that communicate with and extendfrom the rst said steam header, and that telescope into and through theends of some of said imperforate-wall tubes, a second plurality ofperforate-wall tubes that communicate with and extend from said secondsteam header and that telescope into and through the ends of the rest ofsaid imperforate-wall tubes, each of said perforate-wall tubes having abend therein intermediate its steam header and its imperforate-Walltube, a portion of said perforatewall tubes being sealed to andextending through said condensate header to telescope into theirimperforatewall tubes, said steam headers and said perforate-wall tubesdirecting steam into the opposite ends of said heat exchanger, theperforations in each said perforate tube being spaced throughout itslength within the imperforate tube to provide uniform heating of saidheat exchanger even when said steam is throttled, said bends in saidperorate-wall tubes accommodating expansion and contraction of saidperforate-Wall tubes and of said imperforate-wall tubes, said frameextending laterally outwardly beyond the sides and ends of said headers.

4. A steam-heated, air-heating, heat exchanger that comprises aplurality of heat-exchanging tins, each of said heat-exchanging tinshaving a plurality of openings therein, a plurality of imperforate tubesmounted in said openings in said heat-exchanging tins, said impertoratetubes being inclined to the horizontal to drain to the same end- O theheat exchanger, said imperforate tubes projecting outwardly beyond bothends of said plurality of heat exchanger tins, a condensate header thatis connected to the lower ends of said imperforate tubes, a steamheader, a second steam header, a steam pipe communicating with andextending between said steam headers, a plurality of perforate tubesthat communicate with and extend from the first said steam header andthat telescope into and through the lower ends of some of saidimperforate tubes, the upper ends of said some imperforate tubes beingclosed, said perforate tubes being connected in parallel with eachother, a second plurality of perforate tubes that communicate with andextend from said second steam header and that telescope into and throughthe upper ends of the rest of said imperforate tubes, the ends of saidimperforate tubes through which said second plurality of perforate tubestelescope being sealed to said perforate tubes, said perforate tubes ofsaid second plurality of perforate tubes being connected in parallelwith each other, some of said perforate tubes extending through saidcondensate header, each of said perforate tubes having a bend thereinintermediate its steam header and its said impertorate tube, said steamheaders and said perforate tubes directing steam into the opposite endsof said heat exchanger, the perforations in each said perforate tubebeing spaced throughout its length within the impertorate tubes toprovide uniform heating of said heat exchanger even when said steam isthrottled, said bends in said perforate tubes accommodating expansionand contraction of said tubes and of said imperforate tubes.

5. A steam-heated, air-heating, heat exchanger that comprises aplurality of heat-exchanging tins, each of said heat-exchanging tinshaving a plurality of openings therein, a plurality of imperforate tubesmounted in said openings in said heat-exchanging fins, said imperforatetubes being inclined to the horizontaltto drain to the same end of theheat exchanger, said imperforate tubes projecting outwardly beyond bothends of said plurality or" heat-exchanging tins, a condensate headerthat is connected to the lower ends of said imperforate tubes, a steamheader, a second steam header, a steam pipe communicating with andextending between said steam headers, a plurality of periorate tubesthat communicate with and extend from the irst said steam header andthat telescope into and through the lower ends of some of saidirnperforate tubes, the upper ends of said some imperforate tubes beingclosed, a second plurality of perforate tubes that communicate with andextend from said second steam header and that telescope into and throughthe upper ends of the rest of said imperforate tubes, the upper ends ofsaid imperforate tubes through which said second plurality of perforatetubes telescope being sealed to said perforate tubes, some of saidperforate tubes extending through said condensate header, each of saidperforate tubes having a bend therein intermediate its steam header andits said imperforate tube, said steam headers and said perforate tubesdirecting steam into the opposite ends of said heat exchanger, theperforations in each said perforate tube being spaced throughout itslength within the imperforate tube to provide uniform heating of saidheat exchanger even when said steam is throttled, said bends in saidperforate tubes accommodating expension and contraction of said tubesand of said imperorate tubes, the tirst said and said second steamheaders being displaced laterally from said imperforate tubes and beingdisposed outward-ly beyond said ends of said plurality ofheat-exchanging tins.

6. A steam-heated, air-heating, heat exchanger that i 1 1 comprises aplurality of imperforate tubes, said imperforate tubes being inclined tothe horizontal to drain to the same end of the heat exchanger, acondensate header that is connected to the lower ends of saidimperforate tubes, a steam header, a second steam header,a plurality ofperforate tubes that communicate with and extend from the rst said steamheader and that telescope into and through the lower ends of some ofsaid irnperforate tubes, the upper ends of said some imperforate tubesbeing closed, a second plurality of perforate tubes that communicatewith and extend from said second steam header and that telescope intoand through the upper ends of the rest of said imperforate tubes, theupper ends of said imperforate tubes through which said second pluralityof perforate tubes telescope being sealed to the perforate tubes, someof said perforate tubes extending through said condensate header, eachof 4said perforate tubes having a bend therein intermediate its steamheader and its said imperforate tube, said steam headers andsaidperforate tubes directing steam into the opposite ends of said heatexchanger, the perforations in each said perforate tube being spacedthroughout its length within the imperforate tube to provide uniformheating of said heat exchanger'even when said steam is throttled, Ysaidbends in said perforate tubes accommodating expansion and contraction ofsaid tubes and of said imperforate tubes.

7. A steam-heated, air-heating, heat exchanger that comprises aplurality of imperforate tubes, said imperforate tubes being inclined tothe horizontal to drain to the same end of the heat exchanger, each ofsaid irnperforateV tubes being elongated and extending substantially thefull length of the air heating portion of said heat exchanger, aplurality of perforate tubes that telescope into and through the lowerends of some of said trnperforate tubes, the other ends of said someimperforate tubes being closed, a second plurality of perforate tubesthat telescope into and through the ends of the rest of said imperforatetubes, the ends of said imperforate tubes through which said secondplurality of perforate tubes telescope, being sealed to the perforatetubes, the first said plurality of perforate tubes starting adjacent oneend of said heat exchanger and being directed toward the opposite end ofsaid heat exchanger, said second plurality of perforate tubes startingadjacent the said opposite end of said heat exchanger and being directedtoward the lirst said end of said heat exchanger, and a source of steamfor said perforate tubes, each of said perforate tubes having a bendtherein intermediate its imperforate tube and said source of steam, saidperforate tubes directing steam into the opposite ends of said heatexchanger, the perforations in each said perforate tube beingspacedthroughout its length within the imperforate tube to provide uniformheating of said heat exchanger even when said steam is throttled, saidbends in said perforate tubes accommodating expansion and contraction ofsaid tubes and of said imperforate tubes.

8. A steam-heated, `air-heating, heat exchanger that comprises aplurality of heat-exchanging tins, each of said heat exchanger tinshaving a plurality of openings therein, a plurality of imperforatetubes, said imperforate tubes being inclined to the horizontal to drainto the same end of the heat exchanger, each of said imperforate tubesbeing elongated and extending through the openings in said heatexchanger tins from one end of said heat exchanger to the other, each ofsaid imperforate tubes being open at its lower end and closed at itsupper end, a plurality of perforate tubes that telescope into andthrough the lower ends of some of said imperforate tubes, a secondplurality of perforate tubes that telescope into and through the closedends of the rest of said imperforate tubes, the first said plurality ofperforate tubes starting adjacent one end of said heat exchanger andbeing directed toward and terminating adjacent the iirst said end ofsaid heat exchanger, said second plurality of perforate tubes startingadjacent the said opposite end of said heat exchanger and being directedtoward and terminating adjacent the first end of said heat exchanger,and a source of steam for said perforate tubes, said perforate tubesdirecting steam into the opposite ends of said heat exchanger, theperforations in each said perforate tube being spaced throughout itslength within the imperforate tube to provide uniform heating of Saidheat exchanger even when said steam is throttled.

9. A steam-heated, air-heating, heat exchanger that comprises aplurality of imperforate tubes, each of said imperforate tubes beingelongated and extending substantiaily the full length of the air heatingportion of said heat exchanger, said tubes each having an open end tothe same end of the heater and a closed end at the other, each of saidimperforate tubes being inclined downwardly to the open ends tofacilitate drainage, a steam header at one end of saidheat exchanger, asecond steam header at the opposite end of said heat exchanger, a irstplurality of perforate tubes approximately equal in number to one halfthe imperforate tubes extending from said one steam header through theopen ends of said imperforate tubes toward the said opposite end of saidheat exchanger, and a second plurality of perforate tubes equal innumber to the balance of the irnperforate tubes extending from saidsecond steam header through the closed ends of said imperforate tubestoward the said one end of said heat exchanger, whereby steam isintroduced into said heat exchanger at .the opposite ends thereof, theperforations in each of said perforate tubes being spaced throughout itslength within the imperforate tube to assure even steam distribution.

10. A steam-heated, air-heating, heat exchanger that comprises a steamheader at one end .of said heat exchanger, a second steam header at theopposite end of said heat exchanger, a plurality of perforate tubesextending from said one steam header toward and terminating adjacent thesaid opposite end of said heat exchanger, and a second plurality ofperforate tubes extending from said second steam header toward andterminating adjacent the said one end of said heat exchanger, wherebysteam is introduced into said heat exchanger at the opposite endsthereof, a plurality of imperforate tubes equal in number to theperforate tubes, all said imperforate tubes being open at one end andclosed at the other, said imperforate tubes having their open ends tothe same end ot' said heat exchanger and inclined to the horizontal todrain to the open ends, each of said perforate tubes being disposedwithin and encased by an imperforate tube, said iirst plurality ofperforate tubes extending through the open ends of the encasingimperforate tube and said second plurality extending through the closedendof the encasing imperforate tube, said imperforate tubes beingaligned to form a row of'tubes, the said first and said second pluralityof perforate tubes being interleaved Whereby alternating imperforatetubes are tired from opposite ends Vof said heat exchanger, theperforations in said perforate tubes being spaced throughout theirencased length to assure even steam distribution.

References Cited in the tile of this patent UNITED STATES PATENTS

